The goals of the proposed research are focussed on questions of structure-function relationships of complex enzymes, including their kinetic and chemical mechanisms, and on investigations of protein-protein interactions in vitro and in vivo. Major projects include the determination of the 3-dimensional structure of glutamate dehydrogenase, the investigation of the mechanisms of adenylate and adenosine deaminase by NMR techniques, further studies of the interaction of adenylate deaminaae with myosin and its fragments, the investigation of the conversion of G to F action both in solution and in cells using the techniques of recovery of laser induced photobleaching and fluorescence correlation spectroscopy and finally, the development of kinetic theory for complex enzyme systems. An understanding of the behavior of regulatory enzymes is essential for development of ideas about the molecular basis of metabolic regulation in the normal and disease states. Both adenylate deaminase and adenosine deaminase deficiencies have been observed, the former deficiency related to aspects of muscular contraction while the latter deficiency gives rise to serve combined immunodeficiency disease. Actin composes a major portion of the cytoskeletal structure of cells. The polymerization-depolymerization behavior of this protein in non-muscle cells controls shape and dynamic functions such as locomotion, phagocytosis and cytokinesis, while actin in the muscle cells is, of course, essential for muscle contraction.